The invention relates to a lubricant system for sheet and section rolling mills.
2. Prior Art
The application of lubricants containing graphite, alkylene polymers or copolymers, film stabilizers and suspension aids for the lubrication of mandrels in rolling mill trains for the manufacture of seamless pipes is known from Swiss Patent Nos. 596,294 and 609,728. The lubricants are sprayed on the hot mandrel in the form of an aqueous suspension, under which circumstances the water evaporates and a lubricating film is left behind in which the graphite particles are present in the alkylene polymer in a uniform distribution. If the mandrel in the roll stand is introduced into the hollow billet, the alkylene polymer melt forms a hydrodynamic lubricating film, the alkylene polymer burns off while rolling and the gases produced are capable of a separating action. The graphite left behind can absorb momentary and local loading peaks and, in general, acts as a dry lubricant.
The attempt to transfer the lubricant specifically to the sheet and section rolling process was unsuccessful. In view of the substantially longer time which is available for applying the lubricant suspension, the evaporation of the carrier medium and the formation of a uniformly thick, waterproof, lubricating film, it was no longer possible for the known lubricants to suffice.